Poor buying when things expensive they are expert buying top in everything and FOMO in also the middle class are expert on buying highest prices and not just buying they buy it with credit.
Rich buys when something is with good price low price poor buys just to spend money.
Middle class behave like poor too they buying expensive.
You are generalizing the buying behavior of the rich and the poor without presenting datas to back up and just relying on your observation.
I think you should put a disclaimer that this is just your opinion: if you are poor, you cannot afford to buy expensive things; you can only buy what you can afford. I am not really rich and consider myself part of the poor sector, but when it comes to buying and budgeting, my priority is the basic necessities based on my capacity, and when there's excess, I buy budget-friendly items. If you're poor and you overspend, you will have big issues with your budget.
Indeed the generalizing is obvious since someone can't even buy in some shops if poor and this shops are obvious expensive even with common commodities. The OPs views are not concrete enough to really make the point intended.